HADDAM — “An eagle at one o’clock! It’s heading right toward us,” said Andy Griswold, a Connecticut Audubon Society guide. “Judging from its size, it’s a female. It looks like she’s heading back to the nest.”

We watched as the mature bald eagle, with a snow white head and tail and dark body, soared above us, and then landed in a large nest resting in a barren tree.

We were on a bald eagle-watching excursion along the lower Connecticut River. We’d boarded the River Quest tour boat at Eagle Landing State Park in Haddam with about 40 other people, all layered in warm winter garb, for the two-hour guided cruise.

The lower Connecticut is prime winter eagle-watching territory, home to two distinct populations of bald eagles. There are three pairs of year-round nesting eagles, and a dozen to two dozen migrating eagles that winter along the river, drawn to the open water. Though their numbers are increasing nationwide, bald eagles remain on the state’s endangered list.

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We headed farther down the river, and within a few minutes, spotted another eagle perched in a tree. “It’s an immature,” Griswold said. “It looks like a 2-year-old. He has a white belly but hasn’t developed the raccoon mask face yet.”

Griswold shut off his microphone and the captain slowed the boat to a crawl, careful not to stress the eagle, while we looked through binoculars for a closer view. The adolescent was well-camouflaged, its brown speckled body blending with the colors of the branch.

We motored on, breaking through thin sheets of ice, slushy chunks clattering against the sides of the boat. Griswold pointed out a variety of other birds. We saw gulls, Canada geese, hawks, (including a red-shouldered and Northern harrier), swans, mergansers, a common loon, and a black vulture. A harbor seal — only seen during the winter here — bobbed its head in the frigid waters, and then dove beneath the surface. But the eagles stole the show. We left the warmth of the heated cabin again and again, heading out to the deck to watch one soar above or spot another perched on a tree branch. Within an hour or so, we had seen seven bald eagles.

“There’s another nest on the left side,” Griswold said, just as we were about to turn around and head back. The nest was about 5 feet across and 4 feet deep, and, according to Griswold, weighed 400 pounds or more. Heading right for it were two eagles, a male and a female. The female landed in the nest, while the male continued to fly above it. “That’s a good sign,” said Priscilla Wood, a Connecticut Audubon guide also on the trip. “She’s checking it out, preparing the nest, and will hopefully lay her eggs there in a couple of weeks.”

On the trip back to the dock, we spotted three more eagles (for a total of 10) and got a second look at some of the others. There’s something special about seeing these majestic birds in the wild. “It’s amazing,” said Wood. “People come from all over, year after year to see them.”